Directive ultra high frequency antenna



w. s. HALSTEAD 2,492,989

DIRECTIVE ULTRA HIGH FREQUENCY ANTENNA Jan. 3, 1950 5 Sheets-Sheet Filed Feb. 9. 1945 FIG. I 881 I6 x 1 6 4 L W N 20 2| i" W, 5 l7 l7 INVENTOR 4 WILLIAM S. HALSTEAD ATTORNEY Jan. 3, 1950 w. s. HALSTEAD 2,492,989

DIRECTIVE ULTRA HIGH FREQUENCY.ANTENNA Filed Feb. 9, 1 946 5 Sheets-Sheet 2 65 en 62 so INVENTOR Z5 WILLIAM S.HALSTEAD ATTORNEY Jan. 3, 1950 w. s. HALSTEAD DIRECTIVE ULTRA HIGH EREQUENCY ANTENNA Filed Feb. 9. 1946 5 Sheets-Sheet 3 INVENTOR WILLIAM S.HALSTEAD I E N R Jan. 3, 1950 'w. s. HALSTEAD 9 DIRECTIVE ULTRA HIGH FREQUENCY ANTENNA Filed Feb. 9, 1946 5 Sfieets-Sheet 4 I04 1 I05 I06 FIG.7

II? III lol "7 KP v a a ll! w I03 tg i L l/4-4 /l45 f6 '/|47 -)48 /\49 H H [I H H H v ||ov H2 H3 I20 INVENTOR WILLIAM S. HALSTEAD ATTORNEY Jan. 3, 1950 'w. s. HALSTE AD 2,492,989

' DIRECTIVE ULTRA HIGH EREQUENCY ANTENNA Filed Feb. 9, 1946- '5 Sheets-Sheet 5 FIGS I IIIIIIIIIIIIIIIIIIIII/ INVENTOR WILLIAM S.HALSTEAD ATTORNEY Patented Jan. 3, 1950 DIRECTIVE ULTRA HIGH FREQUENCY ANTENNA William S. Halstead, Purchase, N. Y., assignor, by mesne assignments, to Farnsworth Research Corporation, a. corporation of Indiana Application February 9, 1946, Serial No. 646,630

9 Claims.

This invention relates generally to antennae for receiving ultra-high frequency electromagnetic waves, and more particularly relates to a directive antenna array arranged to be tuned to waves of different wave length.

Antenna arrays of the type which comprise one or more directors, a reflector and a principal dipole are known in the art. Such antenna arrays show an appreciably higher gain than a single dipole. They have a better directivity and a large front-to-back ratio, that is, they will receive a wave impinging on the front of the array with a high gain while substantially suppressing waves arriving from the opposite direction. An antenna array which comprises a director, a reflector and a principal dipole is, therefore, well suited for the reception of ultra-high frequency carrier waves modulated, for example, in accordance with a television signal.

It is well known that ultra-high frequency waves are reflected by comparatively small bstacles, such as buildings. Since the carrier waves used for the transmission of television signals are all within the ultra-high frequency range, it is very desirable to provide a television receiving antenna which has a good directivity and a large front-to-back ratio so that it will receive the desired signal from the transmitting antenna while rejecting undesired waves. However, a conventional antenna array of this type may be used only for receiving carrier waves of one frequency or waves within a very narrow frequency band. It is, therefore, desirable to provide an antenna array of the type referred to which may be tuned to different wave lengths and, furthermore, to provide means for rotating the array so that carrier waves from different stations may be received with one antenna or one antenna array.

It is an object of the present invention, therefore, to provide, in an antenna array of the type comprising a plurality of spaced dipoles, means for tuning the array to modulated carrier waves of different wave lengths.

A further object of the invention is to provide an antenna array for receiving ultra-high frequency electromagnetic waves comprising a director, a reflector and a principal dipole which may be tuned and. rotated to any angular position.

In accordance with the present invention, there is provided an antenna array for ultrahigh frequency electromagnetic waves comprising a plurality of extensible conducting members arranged substantially parallel to each other and means for simultaneously extending or retracting the extensible members. In this manner the effective electrical length of the antenna array is varied.

For a better understanding of the invention, together with other and further objects thereof, reference is made to the following description, taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the accompanying drawings:

Fig. 1 is a plan view of an antenna array embodying the present invention;

Fig. 2 is a front elevational View of the antenna array of Fig. 1;

Fig. 3 is a sectional view on enlarged scale of the antenna housing taken on line 3-3 of Fig. 1;

Fig. 4 is a sectional view on enlarged scale of one of the extensible arms of the principal dipole of the antenna array taken on line 4-4 of Fig. 1;

Fig. 5 is a cross-sectional view on enlarged scale of the extensible principal dipole arm taken on line 5-5 of Fig. 4;

Fig. 6 is a front elevational view, partly in section, and on enlarged scale of the director dipole of the antenna array taken on line 66 of Fig. l;

Fig. 7 is a plan view of a modification of the antenna array of the invention;

Fig. 8 is a sectional view on enlarged scale of the antenna housing taken on line 8-8 of Fig. 7; and

Fig. 9 is a diagram of a control circuit for energizing the motors for rotating and tuning the antenna array.

Referring particularly to Figs. 1 and 2 of the drawings, there is illustrated antenna array It) comprising principal dipole H, director dipole l2 and reflector dipole I3 which are arranged substantially parallel to each other. Principal dipole l l, director dipole I2 and reflector dipole l3 comprise each two extensible or telescoping arms l5, l5; l6, l6; and I1, l1; respectively. Director dipole l2 and reflector dipole I3 are spaced a predetermined distance from principal dipole H by means of outer spacing members 20, 2| and intermediate spacing members 22. Spacing members 26, 2| and 22 are made of insulating material.

Arms I5, l5 of principal dipole II and spacing members 22 are supported by upper housing 23 rotatably mounted on lower stationary housing 24. Lower stationary housing 24 is provided with downwardly extending sleeve 25 (Fig. 3) arranged for receiving tubular member 26 which may be secured to sleeve 25 by set screws 21. Tubular member 26 is supported in an upright position in a suitable manner such as by supporting members 28 (Fig. 2).

Principal dipole I director dipole l2 and refiector dipole |3 form an antenna array having a gain which is approximately 6 to 7 decibels higher than that of a single dipole. While a single dipole will receive waves from opposite directions with equal gain, antenna array H] has a front-to-back ratio of 15 to 25 decibels. By Way of example, the spacing between principal dipole II on the one hand, and director dipole l2 and reflector dipole l3, on the other hand, may be approximately one-eighth of the wave length of the modulated carrier wave to be received. The effective electrical length or principal dipole II should be equal to one-half the wave length of the wave to be received. The effective electrical length of director dipole l2 should be slightly less than that of principal dipole while the efiective electrical length of reflector dipole I3 should be slightly more than half a wave length of the wave to be received. When antenna array is arranged in this manner, director dipole l2 and reflector dipole |3- are parasitically excited. It is well known in the art that the dipoles of antenna array In may have different electrical lengths and different spacings from those given above. byv way of example.

Since the effective electrical length of dipoles l2 and I3 can be one-half wave length only for one frequency, means are provided in accordance with the present invention for varying the electrical length of the dipoles, thereby to tune antenna array ID to waves of difierent lengths. As illustrated in Big. 3, there are provided res versible eleetric motors 30 and 3| for rotating an-. tenna array l0 and for extending or retracting 2 l Qf p rleinel finale Re rs b electr m t r 3|! i lllil lll fi l w st i na y housing 24 by disc 32 resting on shoulder 33 of l l? h usi g 2 Elec ric m r 0 i a ra o t ting @1 82 housi a o th end, m ter 30. d'ri i'nin e through a duction gear train indicated at 35. Pinion 34 meshes w in ernal ge r sec d to upper housing 23 by set screws'3 6. Upper housin 23 rests on shoulder 31 ot lower housing 24 and is rotatably secured thereto by pins 38 engageable with annular recess or race 40.

Accordingly, it Will be evident that when electric motor 36 is energized to rotate in either one of two directions, pinion 34 will rotate internal gear 39. Therefore, upper housing 23 will rotate with respect to lower stationary housing 24 in a direction depending upon the direction of rotation of electric motor 30. The control circuit for energizing electriq mgtor 3|] will be explained hereinafter.

Reversible electric motor 3| is provided in upper housing 23 and is arrangedfor extending or retracting arms |5 of principal dipole Electric motor 3| is connected to a power source by leads, not illustrated, which are connected, in turn, to spring contacts 4|, 42 and 43, secured to plate 44 on stationary housing 24. Spring contacts 4|, 42 and 43 bear on and slide over contact 45 and annular slip-rings 46 and 41- 'respectively. Conductors 45, 46 and 41 are arranged in insulating disc 48 mounted in upper housing 23 and secured thereto by set screws 50. Leads 4 5|, 52 and 53 are connected to conductors 45, 46 and 41 respectively, cooperating with spring contacts 4|, 42 and 43.

When reversible electric motor 3| is energized to rotate in either one of two directions, motor shaft 55 is rotated accordingly. Motor shaft 55 bears a worm, npt shown in the drawings, which engages with 'gear 56 secured to insulating drive shaft 51. Ball bearing 58 is provided for supporting the free end of motor shaft 55. Insulating drive shaft 51 is rotatably supported by ball bearings 6D and 6|. Upper housing 23 has two horizontally extending sleeves 62 and 63 for supporting outer tubes 64 of dipole arms |5, |5 of prin pal di ole H.

Each outer tube 64 of one of the dipole arms I5, I5 is mounted in an insulating block 65 supported in turn by sleeves 62 and 63, respectively. Set screw 66 secures insulating block 65 to sleeve 62 while set screw 61, which extends through set screw 66, locks outer tube 64 with insulating block 65. The outer tube 64- of the left hand dipole arm i5 is secured to sleeve 63 in the same manner as the outer tube 64 oi the right hand dipole arm so that further explanation is not necessary. Housing cover 68 closes the upper portion of housing 23.

Insulating drive shaft 51 is connected to worms 1!], extending through outer tube 64, by means of sleeves 1|. Ball bearings 60 and 6| are provided with insulating washers 12 so that worms 10 are electrically insulated from ball bearings 60 and 6| respectively.

When reversible electric motor 3| is energized to rotate in either one of two directions, motor shaft 55 and gear 56 are rotated for driving shaft 51. Hence, worms 10 are rotated in a predetermined direction to extend or retract arms l5, l5 of principal dipole II in unison in a manner presently to be explained.

Telescoping dipole arms |5, |5 are identical in construction, one dipole arm |5 being illustrated particularly in Fig. 4. Dipole arm I5 comprises outer stationary tube 64 and inner tube 15 arranged to be retracted and extended into and out of stationary tube 64 by means of worm 10. To this end, bushing 16 is secured to the free end of inner tube 15. Bushing 16 is provided with internal gear 11 arranged to engage with worm 1B, As shown particularly in Fig. 5, bushing 16 has a key 1.8 engaging with keyway in outer tube 64 to prevent rotation of inner tube 15 with respect to. outer stationary tube 64.

Spring 8 bears against insulating block 65, while spring 82 encircles reduced end portion 83 f warm .0. and be rs. a ainst disc 84, secured to end port on 83- I may be assumed that warm 10 ro a d y electric motor 3| in a direction to draw inner ub towa d he le t. iF s. A cordingly. bushing 16 is advanced toward the left until it compresses spring 3|, Further rotation of worm 16 will disengage bushing 16 from worm 10 whereupon the inwardrnovement of inner tube 15 stops.

When electric motor 3| is now energized to rotate in the opposite direction, spring 6| will urge bushing 16 into engagement with worm 16. Inner tube 15 is then. advanced toward the right of Fig. 4 until bushing 16 compresses spring 82. Further ro ation 9i orm .0 wil dise e it rom u hing 16 here pon the. ou ward. movement inner tube 15 is arres ed. When electric motor 3| is g n ener zed to rotate. in h ppo i e i- 1 rection, bushing 18 is urged into engagement with worm 10 by spring 82, and inner tube 15 is advanced toward the left in the manner previously explained.

From the above description it will be evident that telescoping arms I5, I5 are extended or retracted in unison. For extending and retracting dipoles I2 and I3, inner tube 15 of dipole arm I5 is rigidly secured to outer insulating and spacing member 2I (Figs. 1 and 4). The construction of one of the telescoping arms I6, I6 of director dipole I2, which are identical to arms I1, I1 of reflector dipole I3, is illustrated in Fig. 6. Arm I6 comprises outer stationary tube 85 fixed t spacing member 22 and inner tube 86 arranged to be retracted and extended into and out of outer stationary tube 85. Inner tube 86 is rigidly connected with outer insulating and spacing member 2I.

Hence, it will be seen that when inner tube 15 is extended or retracted with respect to outer stationary tube 64 of principal dipole II, insulating members 20 and 2| will be moved accordingly. Since inner tube 86 of director dipole I2 is secured to insulating member 2|, as is the inner tube of reflector dipole I3, director dipole I2 as well as reflector dipole I3 will be extended or retracted in unison with principal dipole II. Accordingly, dipoles H, I2 and I3 may be extended and retracted in unison by energizing electric motor 3|. Thus, antenna array I0 may be tuned to different wave lengths corresponding to the wave length of the carrier wave to be received. Antenna array I0 will receive waves arriving from the direction indicated by arrows 88 in Fig. 1. Waves arriving from the opposite direction will be substantially suppressed by antenna array I0.

Electric motor 30 preferably is arranged for rotating upper housing 23 and antenna array I0 through an angle of at least 360 degrees so that antenna array I0 may be rotated to receive electromagnetic waves arriving from any direction of the azimuth. Alternatively, if reflector I1 is omitted, antenna array I0 may be rotated through an angle of slightly over 180 degrees.

The modulated carrier wave which is intercepted by antenna array I0 may be obtained through output leads 90, 90 connected by clamps SI, SI to dipole arms I5, I of principal dipole II (Fig. 1). Output leads 90, 90 may take the form of a transmission line to reduce the attenuation losses of the signal. It is also feasible to provide slip rings cooperating with stationary contacts connected to antenna feeder line 90, 30 to allow for continuous rotation of antenna array I0. Since dipoles I2 and I3 act as parasitic elements, they are normally not connected to principal dipole I I through leads or transmission lines.

Referring now to Fig. '1, there is illustrated a modified embodiment of the invention comprising antenna array I00. Antenna array I00 includes principal dipole IOI, director dipole I02 and reflector dipole I03. Dipoles IOI, I02 and I03 are arranged to have their electrical lengths varied and furthermore, the spacing between dipoles IOI, I02 and I03 is also made variable. To this end, dipoles IOI, I02 and I03 are spaced by extensible insulating connecting members I04, I05 and I06, each comprising two telescoping arms. Principal dipole WI and extensible connecting members I05 are supported by housing I01. The modulated carrier wave received by antenna array I00 may be obtained from output leads IIO connected by clamps III to principal 6 dipole IOI. Output leads I I0 may again take the form of a transmission line to reduce signal losses.

Referring now to Fig. 8, there are illustrated two reversible electric motors H2 and H3 arranged, respectively, for extending and retracting principal dipole IOI and for extending and retracting connecting members I05. Reversible motor H2 is supported in housing I01 and is arranged to rotate worms I I4 in the manner described in connection with Figs. 1 to 6, through the intermediary of a gear train housed in gear box II5. Worms 4 extend through outer stationary tubes IIB of principal dipole IOI. Worms II4 are arranged to extend and retract inner tubes II1 (Fig. '7) in the manner explained in connection with antenna array I0 of Fig. 1. Similarly motor H3 is arranged to extend and retract the extensible arms of connecting members I05.

Accordingly the effective electrical length of dipoles IOI, I02 and I03 may be varied by energizing electric motor H2 and their relative spacing may .be varied by controlling electric motor II3. Thus, the spacing'between dipoles IOI, I02 and I03 may be varied always to conform to a predetermined fraction of the modulated carrier Wave to be received. At the same time the effective electrical length of dipoles IOI, I02 and I03 may be varied to conform to another predetermined fraction of the wave length of the same carrier wave to be received.

Housing I01 may be rotated by electric motor I20 arranged to drive gear I2I meshing with gear ring I22 secured to tube I23. Tube I23 may be integral with or secured to housing I01. Inner tube I24 arranged in outer tube I23 is stationary. Disc I25 is secured to the top of stationary tube I24 and has attached thereto spring contacts I26, I21, I28, I29 and I30 cooperating, respectively with annular conductors I32 and I33, contact I34, and annular conductors I35 and I36. Conductors I32 to I36 are arranged in insulating plate I31 secured to housing I01. The electric power supply is connected to motors H2 and H3 through cables I40, I4I connected to spring contacts I26 to I30. Leads I42 and I43 are connected respectively to motors H3 and H2 and to annular conductors I32 to I36.

Referring now to Fig. 9, there is illustrated schematically a control circuit for energizing electric motors H2, H3 and I20. Electric motors H2, H3 and I20, which are reversible, are shown schematically in Fig. 9. By means of switches I44, I45 and I46, I41 respectively, electric motors H2 and H3 may be energized to rotate in either one of two predetermined directions. Similarly, electric motor I20 may be energized to rotate in either one of two predetermined directions by switches I48 and I49. Mo-

tor II2 rotates as long as either switch I44 or 7 I45 is closed, while electric motors H3 and I20 also rotate as long as either of the switches I40 or I41-or either of the switches I48 or I49, respectively, is closed. As explained hereinbefore, electric motor II2 will not cause further movement of inner tube II1 of principal dipole IOI when inner tube H1 is either in its fully extended or in its fully retracted position. The same applies to electric motor H3 which will not cause further motion of connecting members I05 when their inner tubes are in their fully extended or in their fully retracted positions. Thus each of the motors H2, H3 and I20 may be controlled independently thereby to vary the escapee electrical length of dipoles IBI, I02 and I03, their relative spacing and the angular position of antenna array IOU.

It is also feasible to energize and de-energize electric motors H2 and H3 simultaneously, for example, by means of two common switches. In that case, the gear ratio between the motors and their driven members should be such that the ratio between the effective electrical length of dipoles IOI, I02 and I03 and their relative spacing always remains constant. 1 7

Electric motors 3t and 3| (Fig. 3) may also be controlled by means of an electric circuit such as that illustrated in Fig. 9. Thus electric motors H2 and H3 may be replaced by motors 30 and 3| in the circuit of Fig. 9. These motors may be controlled by switches I44 to I 47 in the manner already described.

The supporting structure and mechanism for adjusting the antenna provided in accordance with this invention is disclosed herein purely by way of example as it is not intended that the invention shall be limited to such structure and mechanism. It will be obvious to those skilled in the art that there are many alternative supporting structures and adjusting mechanisms which may be substituted for those described herein.

While there has been described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An antenna array for ultra-high frequency electromagnetic waves comprising a plurality of extensible dipoles arranged substantially parallel to each other, means for simultaneously extending and retracting said dipoles, thereby to vary the efiective electrical length of said dipoles,

extensible connecting members for spacing said dipoles, and means for simultaneously extending and retracting said connecting members, thereby to vary the relative spacing of said di poles.

2. An antenna array for ultra-high frequency electromagnetic waves comprising a principal dipole, a director dipole, and a reflector dipole, each of said dipoles including two telescoping arms, extensible insulating connecting members for spacing said dipoles substantially parallel to each other, means for simultaneously extending and retracting said arms, thereby to vary the efiective electrical length of said dipoles, and means for simultaneously extending and retracting said members, thereby to vary the spacing between said dipoles.

3. An antenna array for ultra-high frequency electromagnetic waves comprising a principal dipole, a director dipole, and a reflector dipole, each of said dipoles including two telescoping arms, extensible insulating connecting members for spacing said dipoles substantially parallel to each other, means for extending and retracting said arms in unison, thereby to vary the eifective electrical length of said dipoles, means for extending and retracting said members in unison, thereby to vary the spacing between said dipoles, and means for rotating said antenna array to any angular position.

4. An antenna array for ultra high frequency electromagnetic waves comprising a housingmember, a principal dipole extending therefrom, a director dipole, a reflector dipole, each of said dipoles including two oppositely extending telescoping arms, spaced telescoping insulating connecting members extending from said housing to the midportions of said director and reflector dipoles and from the ends of said principal dipole to the ends of said director and reflector dipoles for supporting said director dipole and said refiector dipole in parallel relation to said principal dipole, a motor in said housing for driving the connecting member extending from said housing to change the spacing of said dipoles, and another motor connected to the arms of said principal dipole for changing their length and moving the connecting members connected thereto for changing the length of said other dipoles.

5. An antenna array for ultra-high frequency electromagnetic waves comprising a housing member, a first dipole extending therefrom, a second dipole, a third dipole, each of said dipoles including two oppositely disposed extensible arms, spaced extensible insulating connecting members extending from said housing to the midportions of said second and third dipoles and from the ends of said first dipole to the ends of said second and third dipoles for supporting said second dipole and said third dipole in parallel relation to said first dipole, a motor in said housing for driving the connecting member extending from said housing to change the spacing of said dipoles, and another motor connected to the arms of said first dipole for changing their length and moving the connecting members connected thereto for changing the length of said other dipoles.

6. An antenna array for ultra-high frequency electromagnetic waves comprising a housing member, a principal dipole extending therefrom, a director dipole, a reflector dipole, each of said dipoles including two oppositely extending telescoping arms, spaced telescoping insulating connecting members extending from the ends of said principal dipole to the ends of said director and reflector dipoles for supporting said director dipole and said reflector dipole in parallel relation to said principal dipole and a motor connected to the arms of said principal dipole for changing their length and moving the connecting members connected thereto for changing the length of said other dipoles.

7. An antenna array for ultra-high frequency electromagnetic waves comprising a housing member, a first dipole extending therefrom, a second dipole, a third dipole, each of said dipoles including two oppositely disposed extensible arms, spaced extensible insulating connecting members extending fromthe ends of said first dipole to the ends of said second and third dipoles for supporting said second dipole and said third dipole in parallel relation to said first dipole and a motor connected to the arms of said first dipole for changing their length and moving the connecting members connected thereto for changing the length of said other dipoles.

8. An antenna array for ultra-high frequency electromagnetic waves comprising a housing member, a principal dipole extending therefrom, a director dipole, a reflector dipole, each of said dipoles including two oppositely extending arms, spaced telescoping insulating connecting members extending from said housing to the midportions of said director and reflector dipoles and from the ends of said principal dipole to the ends ."(5 of said director and reflector dipoles for supporting said director dipole and said reflector dipole in parallel relation to said principal dipole and a motor in said housing for driving the connecting member extending from said housing to change the spacing of said dipoles.

9. An antenna array for ultra-high frequency electromagnetic waves comprising a housing member, a first dipole extending therefrom, a second dipole, a third dipole, each of said dipoles including two oppositely extending arms, spaced telescoping insulating connecting members extending from said housing to the midportions of said second and third dipoles and from the ends of said first dipole to the ends of said second and third dipoles for supporting said second dipole and said third dipole in parallel relation to said first dipole and a motor in said housing for driving the connecting member extending from said housing to change the spacing of said dipoles.

WILLIAM S. HALSTEAD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Meyer May 30, 1933 Clavier Jan. 21, 1936 Sullinger July 11, 1939 Jenkins Apr. 30, 1940 Martin Apr. 22, 1941 Benton et al Oct. 28, 1941 Benton et al. Nov. 18, 1941 White May 19, 1942 Mims Aug. 11, 1942 Peterson Dec. 3, 1946 

